Rearrange character C++

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2.33/5 (2 votes)

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I'm trying to write a program in C++ that takes the first character of users input and puts it to the end. Do program will do that for n tines

Eg.

User Input: 'stack'

'How many times should I rotate?'

User Input: 2

Output: 'ackst'

What I have tried:

C++

#include <iostream>
#include <string>
using namespace std;

int main()
{
	int K;

	string S;
	cout << "------------------------------------"<<endl;
	cout << "Enter a word: ";
	cin >> S;
	cout << "------------------------------------"<<endl;

	if(S.length() >1000)
	{
	cout << "------------------------------------"<<endl;
	cout << "Too many characters"<<endl;
	cout << "------------------------------------"<<endl;
	}
	
	if(S.length() ==1)
	{
	cout << "------------------------------------"<<endl;
	cout << "Not enough characters"<<endl;
	cout << "------------------------------------"<<endl;
	}
	
	if (S.length() <=1000 && 
  S.length() !=1)

        {
	cout << "Times of rotation: ";
	cin >> K
	}
}

Posted 7-Dec-18 1:27am

Member 14081190

Updated 7-Dec-18 11:46am

Leo Chapiro

v2

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2 solutions

Solution 2

In an alternative approach, you could use string::substr

C++

#include <iostream>
#include <string>
using namespace std;


void rotate (string & s, size_t r)
{
  r %= s.length();
  if ( r == 0) return;
  s = s.substr(r,s.length()-r) + s.substr(0,r);
}

void show_decorated(const string & message)
{
  cout << "------------------------------------\n";
  cout << message << '\n';
  cout << "------------------------------------\n";
}

int main ()
{
  int K;
  string S;
  cout << "------------------------------------\n";
  cout << "Enter a word: ";
  cin >> S;
  cout << "------------------------------------\n";

  if( S.length() > 1000)
  {
    show_decorated( "Too many characters" );
    return -1;
  }
  if(S.length() <= 1)
  {
    show_decorated("Not enough characters");
    return -1;
  }

  cout << "Times of rotation: ";
  cin >> K;
  rotate(S,K);
  show_decorated(S);
  cout << endl;

}

Posted 7-Dec-18 11:46am

CPallini

Updated 7-Dec-18 11:47am

v2

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Leo Chapiro · Accepted Answer · 2018-12-07T02:08:00

Try this:

C++

if (S.length() <= 1000 && S.length() != 1)
{
	cout << "Times of rotation: ";
	cin >> K;

	int L = S.length();

	for (int ii = 0; ii < K; ii++)
	{
		char chFirst = S[0];

		for(int i = 0; i < L - 1; i++)
			S[i] = S[i+1];

		S[L - 1] = chFirst;
	}
			

	cout << S;
}

A short explanation:
- we save the first character
- loop n- times, where n the rotation is.
- inner loop: replace the first char with the second, the second with the third and so on
- set the first character to the and of the string